Temperature-indicator.



J. E. ROBINSON.

TEMPERATURE INDICATOR.

APPLICATION FILED APR. 13. m4.

Patented Nov. 23, 191 5.

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JAMES E. ROBINSON, OF CHICAGO, ILLINOIS.

TEMPERATURE-INDICATOR.

To all whom it may concern:

Be it knOWn that 1, JAMES E. lRoBINsoN, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Temperature-Indicators, of which the following is a specification.

This invention relates to improvements in temperature indicators and more particularly to an indicator adapted to be mounted in the filler cap of an automobile radiator.-

It is a well known fact that the temperature of the cooling water of an internal combustion engine should be maintained at a point some ten or fifteen degrees below boiling for the most efiicient operation of the engine. If the temperature increases to boiling point it is obvious that the comparatively small suppy of water carried in a motor car radiator will be rapidly dissipated as steam, and the lubrication of the cylinder walls and piston materially interfered with by carbonization of the oil. On the other hand if the temperature of the cooling water is very low there is a marked decrease in efiiciency due to the cooling of the combustion chamber and consequent slow propagation of flame. If the temperature falls below the freezing point, the radiator, cylinder jacket and piping are apt to be burst by the freezing of the water.

One of the objects of my invention is to provide a water temperature indicator, easily read from the seat of a car, so that the operator may at all times be aware of the exact temperature of the water in the cooling system. If the temperature takes a sudden rise it is evident. that some part of the system has become inoperative, as for example, by the clogging of the circulating pump, the breaking of a fanbelt or the like. If the operator observes a drop in the temperature below that of normal operating condition, he is thus notified of the necessity for blanketing the radiator and hood in order to prevent too rapid cooling. If the temperature drops near the freezing point, he is warned that non-freezing solution of some sort should be added to the cooling water to prevent bursting of his cylinder jacket or radiator.

Another object of my invention is to pro vide such an indicator, in which the part projecting above the top of the radiator filler cap is surrounded by a dead air cham- Speciflcation of Letters Patent.

Patented-Nov, 23, 1915.

Application filed April 13, 1911. Serial No. 831,398

her in order that the rush of air due tothe motion of the vehicle will not affect the reading of the temperature indicating fluid.

Another object of my invention is to provide a reading scale for my improved indicator, which can be easily read from a distance, indicating the range through which the temperature of the water may vary withwith a protective metallic casing. having openings therein for observation of the thermometer stem.

Another object of my invention is to provide convenient means for correctly setting the spirit, or mercury tube in the casing, after the former has been properly calibrated.

Other objects will be apparent to those skilled in the art from the following. description and drawings, wherein,

Figure 1 is a side View of my improved temperature indicator showing it attached to the filler cap of an automobile radiator. Fig. 2 is a vertical, sectional view on the line 22 of Fig. 1. Fig. 3 is'a horizontal, sectional view on line 3-3 of Fig. 2, and; Fig. 4 is a horizontal, sectional view on the line 44 of Fig. 2.

Referring to the drawings, the numeral 10 indicates a radiator shell, in which is secured a threaded nipple 11, engaged by the threads of the filler cap 12.

My improved indicator comprises a thermometer tube or stem 13, terminating at its lower ends in a fluid containing bulb 14,

from which the indicating fluid 15 rises in the small bore 16. This thermometer tube is preferably made of triangular form as indicated in Fig. 3, thus magnifying the diameter of the liquid column in order that it may be more readily observed from a distance. A tubular jacket 17 surrounds the lower portion of the thermometer tube. and

is sealed to the same by means of some suitable cement, such as plaster of Paris, or the tube 21 is threaded for engagement with a threaded opening in the filler cap 12, said threads extending up to the shoulder 23 formed by the enlarged upper section 22.

Therearward face of the tubular casing 22, that is, the face viewed by the driver of the car, is provided with a vertical opening through which the thermometer may be easily read. The outline of the opening is in the nature of three intersecting circles, providing two pairs of opposite, inwardly projecting prongs or pointers 2 124. It is obvious that two pairs of pointers 24 and 2 1' divide the column of the thermometer into three areas or zones, the upper being designated by the letter A, the central zone B and lower zone C. The thermometer is positioned in the casing so that when the top of the indicating fluid is in zone B, between the pointers 24-21, the driver is informed that the circulating system of his engine is operating properly and at the most efficient temperature. If the fluid drops below the point 2 1 into zone C, the temperature of the cooling water is too low and means should be taken to increase the temperature in order to bring the reading point of the thermometer into zone B. If the top of the fluid rises above the point 24 into zone A the engine is getting too hot and means should be taken to lower the temperature of the cooling medium.

A glass tube '25 fits within the cylindrical casing 22, a rubber washer 26 or the like at the bottom of the enlargement providing a resilient abutment or cushion for the lower end of the tube. A cover or cap 27, makes threaded engagement with the upper end of the casing 22 and completely closes the area within the casing. The concentric dead air space, or column surrounding the part of the thermometer tube exposed above the filler cap protects it from the influence of temperature changes outside of the radiator, and

the cooling effect of the air due to rapid motion of the vehicle.

A vertically arranged rectangular or ovate slot 28 is provided in the front side of the casing, that is, the side away from the driver, so that the temperature of the cooling water may be observed from the front of the car when it is at rest, without reference to the zones A, B and C.

In order that the thermometer may be in serted within the tubular casing with a fixed scale reading always in register with one of the pointers 2424, I calibrate the same with reference to the distance between the lower pointer 24: and the lower end of the tube 21, indicating on the thermometer-com taining tube 17, the point which should register with the lower end of the tube 21. The thermometer is then readily assembled in its casing by inserting tube 17 within the casing 21 and moving it up to the indicating point and then placing solder 29 around the lower end of the casing 21, to securely fasten it to the thermometer containing tube 17.

It is obvious that this improved indicating device may be advantageously used on other apparatus and whereas I have shown it as particularly adapted for mounting in the ller cap of an automobile radiator, by slight changes it may be adapted to a variety of uses with other apparatus where it is desirable to indicate t e temperature within a receptacle.

Having described my invention, what I claim is A temperature indicator of the class described comprising a thermometer stem, a supporting and incasing member having a reading scale and a head against which the upper end of said stem abuts, a metallic tube permanently sealed to the lower portion of the stem, a downwardly projecting portion on said member provided with an opening through which extends the thermometer stem and its metallic tube, and means for sealing the oint between said porjecting portion and the metallic tube substantially as and for the purpose set forth.

In testimony whereof I hereunto set my hand in the presence of two subscribing witnesses.

JAMES E. ROBINSON. In the presence of Fonr'm BAIN, MARY F. ALLEN. 

